A letter from the remote and land of Australia turns the Robinson household upside down. An old friend urges Dr. Robinson to leave his thriving practice in Switzerland and move to the land down under, where there is a painful shortage of doctors.

Becca Robinson has no doubts about the exciting move, but her older brother Fritz is afraid it will devastate his career plans. After first deciding to stay with relatives, Fritz leaps aboard the ship and joins his family in their journey to a new life.

As the Robinsons travel down the Rhine, a riverboat con man finds Becca easy prey. A famous diva helps to unmask the swindler.

The Robinsons set sail from England, and their adventures at sea begin. Jack's antics cause problems with fellow passengers, but tensions are soothed when Dr. Robinson delivers the couple's first baby, born at sea.

Fritz's new friend Emily is distressed by a family quarrel, and may have to leave the ship at the next port. Becca gets into the act and aggravates everyone but her good intentions are recognized and everything works out in the end.

The shipboard Christmas pageant is cut short by a violent storm. As the elements rage, the ship runs aground, and passengers escape in lifeboats. But Fritz is missing, and the Robinsons are stranded on board.